A Discrete Element Analysis of the Indirect Tensile Failure in Hollow Brazilian Discs of Bedded Geo-Materials

The hollow Brazilian disc-type specimens of transversely bedded geo-materials were numerically modeled using the particle discrete element codes PFC2D for investigating the mechanical behavior and failure mechanism of the transversely isotropic rocks. The breakage mechanism and tensile strength of the transversely isotropic layered rocks were numerically studied using the hollow disc specimens. This numerical code was calibrated by the indirect tensile testing accomplished on the Brazilian disc specimens in the laboratory. Then, about 21 modeled hollow disc specimens with an outer diameter of 100 mm were considered. These specimens were established with two bedding layers in which the first one was the weakest layer with low mechanical characteristics and the second layer had relatively high mechanical parameters (close to those of the intact geo-material). In this study, the angle of the first (weak) layer relative to the applied loading direction varied. The angle of the second (stronger) layer was kept constant (i.e., 180° with respect to the loading direction). The numerical results showed that tensile cracks could develop in the weak layer, and their number decreased as the weak layer’s thickness increased. On the other hand, the strong layer experienced no failure during the loading process.